The present invention relates to converters of thermal energy into electric energy and, more particularly, to film thermoelements.
There are known film thermoelements comprising two branches formed by films of semiconductor material of the p- and n-types of conductivity, which films are interconnected by means of commutation buses, their end face surfaces being in contact with a hot bus on one side and with a cold bus on the other.
In such thermoelements the heat flux flows along the film branches of the thermoelement having an extremely low s/1 ratio, where s is the cross-sectional area of a branch, equal to the product b .times. h, where h is the thickness of the film of a p- or n-type semiconductor material, b is the width of the film and 1 is the length of the film making up the branch of the thermoelement.
In the existing film thermoelements 1&gt;b and 1&gt;&gt;h; as a result, only weak heat fluxes G are passed along the branches, said heat fluxes being proportional to s/1. This, in turn, accounts for an extremely low amount of electric power taken from a thermoelement of this type.
The power output of this type of thermoelement may be increased in two ways.
The first way is to increase the cross-sectional area s of the branches of a film thermoelement, for example, by using in each branch a large number of films in parallel connection. This augments the total thickness of the semiconductor films forming the branches of the thermoelement, which, in turn, results in a more powerful heat flux. Solving this problem, however, is a very long and laborious process.
The other way is to arrange the thermal buses on the top and at the bottom of the semiconductor films which form the branches of the thermoelement. In this case the heat flux is perpendicular to the plane of the film, and a temperature drop is produced over a distance h equal to the thickness of the film, which, as has been stated above, is very small. In the case under review the heat flux Q is proportional to the relation (1 - b)/h which is very great. This leads to great thermal losses on the commutation buses since the thermal and electrical resistance of the film is proportional to the relation h/(1 .times. b) which is very small and is comparable with the thermal and electrical resistance of the contacts between the semiconductor film and the commutation buses.